With the recent advent of aerobic type exercises such as swimming, cycling, jogging and tennis there has been a corresponding upsurge in the rate of deaths relating to cardiovascular exertion. The frequency of heart failures occurring, for example, in winter months due to the exertion on the heart by the over zealous snow shoveler is now occurring throughout the remaining seasons due to heart exertion caused by physical fitness enthusiasts. A person following the current fashion of weight reduction by early morning jogging may lose as much as 20 pounds in a month and may also lose his life. The sudden and continued exertion above a critical limit upon the heart caused by the tremendous amount of blood transport and oxygen consumption required results in a breakdown of the heart structure and, if immediate medical attention is unavailable, death may result. The unfortunate factor common for most cases of coronary failure due to overexertion is that the victim never knows when to stop and death in most cases could have been avoided if the victim didn't continue his exercise.
The heart muscle, like any other vital organ, can build up tolerances to long and continued exertion if given time to develop sufficient cellular structure to accommodate the added workload and to provide for the increased blood handling capacity. By gradually exposing the heart to periods of temporary exertion over increasing periods of time, the body as a whole adapts to a lower oxygen consumption requirement and the heart readily supplies the increased demands for blood flow.
Several devices are currently available for monitoring the pulse rate activity of the human heart. For example, U.S. Pat. No. 3,792,700 describes a technique for indicating the pulse rate of an inactive user by electrodes placed under the armpits of a user. This technique provides an indication of the pulse rate of an inactive user and signals when a coronary problem exists. U.S. Pat. No. 3,802,698 incorporates a pulse rate measuring device with a stationary exercise control system and signals when a particular pulse rate value is reached. U.S. Pat. Nos. 3,742,937; 3,807,388 and 3,863,626 describe miniature pulse monitoring devices that can be worn by persons undergoing physical fitness activities to indicate when a predetermined pulse rate has been exceeded.
The aforementioned examples of the prior pulse rate indicators provide some means for detecting and monitoring the pulse rate of a person undergoing physical exertion and for indicating when the exertion is excessive, but are not tailored to the individual physiological characteristics of the user.